STUDIES REGARDING THE THERMAL-STABILITY OF SOME COORDINATION POLYMERS- POLYDIPHENYLPHOSPHINATES AND POLYDIALKYLPHOSPHINATES OF CR(III), FE(III), MN(II), CO(II), NI(II) AND UO22+

In order to obtain coordination polymers resistant at high temperature s, many compounds from a new class of coordination polymers, having as ligands anions of diphenylphosphinic acid and dialkylphosphinic acid, have been prepared and studied; this started in 1962. In this paper, we report our continuing studies, recording and discussing TG curves o btained using a MOM Budapest derivatograph. The effect of oxygen from air versus temperature on the above-mentioned coordination polymers wa s examined. The temperatures that corresponded to the beginning and en d of the thermal decomposition and also the temperatures at which 10% and 25% of the samples are transformed to volatile compounds were used to estimate the thermal stability. The kinetic parameters of the ther mal decomposition were also computed. These studies were made using sa mples of coordination polymers with the general formula [M(R(2)PE(2))( x)](n) where, M is Cr(III), Mn(II), Fe(III), Co(II), Ni(II) and UO22+, R is C2H5, C4H9 and C6H5 radicals, E is oxygen or sulphur, x is 2 or 3, and n is the polymerization degree. Discussing the experimental dat a we conclude that the thermal stability is higher: in nitrogen atmosp here; for polymers that contain the phenyl radicals and Mn(II); and fo r the same cation in the series: polyphosphinate > polythiophosphinate > polydithiophosphinate. The reaction order and the activation energy calculated using the Freeman-Carroll method presented values between 0.75 and 0.95 and 125 and 464 kJ mol(-1) respectively.